Firefighters are making progress against California's largest wildfire of the year but face challenges from expected thunderstorms. Similar dry, hot conditions are posing threats across the fire-stricken West.
Key Points
Containment of the Park Fire at 27%
Fire started by arson in a park in the Sierra Nevada foothills
Challenges from hot, dry weather and rugged terrain
Evacuation orders in effect for 22 fires across the western U.S.